DISTRIBUTION OF YOUNG STAGES OF EUPHAUSIA SUPERB A 141 



17-5-18 mm. These two maxima were not connected with the stage of development, for in the lower 

 group Furcilia 6 and adolescents were present in approximately equal numbers, while in the upper 

 the larvae were entirely adolescent. It cannot be, therefore, that the second length group is the re- 

 sult of the larvae moulting, with sudden increase of length from Furcilia 6 to adolescent. The first 

 length group thus does not moult directly to the second. 



At St. 959 there was a similar distribution of length groups, but not quite so well-defined. The 

 larger group is still too small to be regarded as the young adults of the ensuing season. Our figures 

 for the average length of adolescents show that normally they reach about 20 mm. by the end of the 

 first half of their second summer season, so that they would be much larger nine months later. It is 

 more likely that at each of Sts. 954 and 959 we are dealing with two different broods belonging to the 

 same year class. It may be that the larger group originates from eggs spawned very early in the pre- 

 vious season or, as suggested by John in his report, concerning a similar length distribution of larvae 

 late in the circumpolar cruise, the size difference may be due to better conditions for growth in cer- 

 tain areas, such as a more abundant diatom flora. 



At St. 955 young E. superba representing Furcilia 6 and adolescents were taken, with the latter 

 predominating. At St. 956 only two Furcilia 6 were taken and at St. 957 three undetermined stages. 

 One adult and eighty young were taken at St. 959, with adolescents predominating. 



{e) Bellingshausen Sea, October-November 1932 (Sts. 968-1003). 



The second portion of the W-shaped track from New Zealand to Magellanes was made in condi- 

 tions which prevented the ship from reaching the ice-edge. Fuel was short and a prolonged gale 

 interfered with the programme arranged. The ship turned northwards again in 63° 57' S, loi " 16' W 

 with clear water to the southward. No krill was taken. 



From Magellanes another V-shaped cruise was made at the end of October and beginning of 

 November, south to the edge of the pack-ice and then north-east roughly parallel to the Graham 

 Land Coast. 



Young krill, but no adults, occurred in very small numbers in nine of the ten stations made along 

 and near the pack-ice — the total number from both the oblique i-m. and 70-cm. nets and the hori- 

 zontal surface nets was only 170 individuals, 113 of which were taken at the northernmost station 

 (1003). Furcilia 6 predominated, whereas south-east of New Zealand in September adolescents and 

 Furcilia 6 were in about equal numbers if the second larger length group is ignored; adolescents 

 greatly preponderated if the larger group is included. 



The Bellingshausen Sea krill were measured by John, and later the small numbers taken at Sts. 

 1027 and 1 03 1, and 200 young from a large haul of mixed old and young krill from St. 1029, were 

 measured. These stations were to the north-west, south-west and west of South Georgia, far from the 

 ice. A third batch of young krill, taken from six stations near to the Weddell Sea ice (Sts. 1034, 

 1035, 1039, 1041, 1044, 1047) was measured by John. 



The length-frequency distribution of these three samples of krill is shown in the graphs in Fig. 61. 



The young krill from the Bellingshausen Sea {A) were taken between October 29 and November 2 ; 

 they were small. An analysis of the young krill taken south-east of New Zealand seven weeks 

 earlier showed it to be composed of two size groups falling about the lengths of 12 and 20 mm. The 

 majority of the Bellingshausen Sea krill were 12-14 mm. long and would have been a millimetre or 

 two less in early September. 



The young euphausians from the open sea to the west of South Georgia {B) and those from the 

 Weddell Sea ice-edge (C), all of which fall about the lengths of 24-25 mm., were taken between 

 November 18 and 30, that is two to four weeks later than those from the Bellingshausen Sea. The 

 period between the observations is not suflicient to account for the great difference in size. The 

 similarity of the two populations represented by the curves {B) and (C), together with Deacon's dis- 

 covery of the existence of a constant flow of water from the Weddell Sea towards the Shag Rocks, 

 makes it certain that the krill in the open water to the west of South Georgia was of Weddell Sea 

 origin. It is suggested by John that better conditions for growth in the ice-free water, such as the 



